Why should you take Handcuffs just to handle Tommy? From a naive action-cost perspective it doesn't seem to make sense: you just spent 2 resources, a card, and an action to save yourself 2 actions, in a class that isn't known for having an excess of resources. Effectively you're playing a Swift Reflexes, which isn't even a particularly good card on Rogues, much less Guardians.

But there are three important reasons why you would do this. Firstly, Cho will almost certainly draw through his deck every scenario, meaning that there's a good chance of seeing Tommy twice if not for Handcuffs. Secondly, you only need to pass a single test, not 3, which is particularly important at higher difficulties. Thirdly, it means you can draw safely during your turn. Since it usually will takes 3 actions to clear Tommy (baring Beat Cop (2), Dogs, and One-Two Punch), it'll feel terrible taking a draw action and find Tommy while trying to refill your hand. Banking an action with Handcuffs will save you from being smacked around by Tommy for a turn, or deal with him easily if he's drawn by an Overpower or Glory.

I feel I need to provide the contrary viewpoint and say that this card, while usable, is really pretty disappointing. I want to like this card because it forms part of the major theme of mystics. There are spells like Shriveling that let Mystics use Will to be good at fighting, there are spells like Rite of Seeking that let Mystics use Will to be good at investigating, and this is ostensibly the spell that lets Mystics use Will to be good at evading. Unfortunately Mists is really weak compared to these other two. The problem is that Shrivelling is much better than a basic fight action (+1 damage), and Rite of Seeking is much better than a basic investigator action (+1 clue), but mist is not really better than a basic evade action. In theory it gives you an action compression bonus just like the other two (+1 move), but that bonus is far less useful because you rarely want to use it. Indeed, it is so much less useful that it is barely makes up for the penalty of sometimes having to discard a card.

The most important use of evade is to keep an elite monster distracted while the party fights it, but if you are doing this you do not want to move away from the monster. Evade can be good against regular monsters for many characters who are not fighters and find it much easier to evade and let other characters do the fighting. But if you are a Mystic you have the option of taking your fighting spell instead, and it is almost always better to do 2 damage to the monster rather than evade the monster. Evasion can be better against monsters with 3+ Health if you can just leave and ignore them, and the +1 move bonus of Mists seems primarily designed for that exact circumstance. But FFG seems really reluctant to put many such monsters in their adventures, it seems like the great majority of the monsters either have Hunter, or have doom on them, or are otherwise better to kill than leave alone. To be fair, there are some monsters you can run away from, and there are some monsters you are better off evading than fighting because you get a penalty if you kill the monster, and here is where Mystic evading shines. The problem is that even in these cases +1 move isn't a great bonus because often when you encounter the monster you are not done investigating or otherwise interacting with the location it is on, and you still don't want to move away. This is compounded by the fact that Mists is not an event, it is an asset, so while it is conditionally useful, you have to play it before you know whether that condition will be satisfied; once you have played it, you are likely to end up using it mostly at times when you don’t want to run away.

Despite all of this, mists would be fun to play around with if it didn't take up a slot. But the fact is that it takes up an arcane slot, a slot that is in very great demand for most Mystics. This means that even if you decide to have a bit of whimsy and put this in your deck, you often regret playing it rather than waiting for a better spell to put in that precious slot. Mists is best for characters who have high Will and low Dex who have access to Mystic cards but don’t really use their arcane slots and have the resources to fool around with conditionally useful cards. Not a very broad selection of characters, to say the least.

If you don't have many expansions, Mists is a better card because you do not have many other options, if the only way you can fight is with the two copies of Shrivelling in your deck you may want to put this card in just so you can do something when you don't have Shriveling. On the other hand, if you have lots of expansions, the real nail in the coffin for this card might be Sword Cane, which lets you use Will to evade without spending charges or using an arcane slot.

Worth noting this card can have extra value in Return to The Forgotten Age, where the updated explore mechanic means you'll either get to this card faster, or possibly even shuffle it into the Exploration deck for a nice surprise while exploring. If it goes into the Exploration deck, it's also protected from encounter deck shuffling and can be searched using Exploration deck supplies.

Promise to break the promise if you just want 10 curses:

• Eye of the Djinn, "Lucky" Penny or Forbidden Tome
• Or seal them on Favor of the Moon
• Turn them to blesses with Tides of Fate and seal them on Favor of the Sun, Rite of Sanctification

If you want to keep it, the promise only matters on your turn.

• "play" is during your turn, i can't think of a way around that (rogue cards like Quick Thinking specify "...like it's your turn")
• "Draw" is hard outside your turn cause most rogue cards do so during your turn like Pickpocketing or Lucky Cigarette Case. All In, Manual Dexterity could work
• "Commit" should be easiest, during mythos or other player turns.

Usually I build decks focused on 1 or 2 skills so I'm not interested in having a bonus to all the 4 skills. Plus you now have to stop drawing / playing / committing.
But rogues have a few events that let you add up 2 skills (for example Slip Away) and now you have a +2 bonus which is quite nice ! And a +4 bonus to the basic action (considering that the average basic skill value is 3). For example Jenny Barnes investigates as a basic action with an intel value of 4 but if she plays Breaking and Entering she does with a value of 8, which means she probably can do without committing a skill.
An other interesting thing is that the Winifred Habbamock pack contains upgraded versions of the "2-skills events" that can return to your hand at the end of the turn (Cheap Shot, Slip Away) and so ensure you to get these great bonuses more than once per copy of the card.
Now, which investigators are the most interesting to play Geas with this in mind ?

Finn Edwards plays these events with a skill value of 9 or 10 (3 + 4 or 4 + 4 and then the + 2 from Geas), and up to 12 if playing Lola Santiago. Plus the evade event (Slip Away) can be played as a free action.

"Skids" O'Toole has a 10 total skill value for the 3 non-willpower skills (compared to Finn's 11) but he has the advantage to be able to play Chuck Fergus and these events have the Trick trait ! Most of the time, Chuck will probably not be used for the +2 bonus but to make the event both fast and 2 resources cheaper which makes them free fast events played with a skill value of 9 (+ other passive bonuses) that can potentially return to your hand.

When checking cards containing "add your" to find events adding to skills I also found Ethereal Form, Read the Signs and Spectral Razor so we can look at the 2 rogue/mystic investigators: Sefina Rousseau and Dexter Drake. The first has already the possibility to play an event several times but she can achieve a really high value only with Read the Signs. The second one is likely built around assets.

Wendy Adams has access to this card and can also probably be played without committing cards thanks to her ability to re-draw chaos tokens (and so to try to achieve a less high skill value in the first time). She can play Cheap Shot and Slip Away with respectively a skill value of 7 and 9 and could also use Suggestion with a skill value of 10 in a deck trying to limit the amount of fights. She can also play On Your Own to decrease the cost of survivor events to keep the resources for the rogue ones.

Of course other rogues and Lola Hayes can also play it but I'm not trying to be exhaustive, only to describe which decks I'm the most interested in trying this card in.

And I have not discussed the 2 other possibilities (not drawing and not playing): not drawing seems limiting in case you end in a situation in which you need a card still in your draw pile, and not playing would require committing a lot (with I usually do in Minh Thi Phan's decks) and/or relying on your assets (so no munition, supply, key, ...).